This week we were supposed to measure the analog levels and digital signals in an input device.
We used oscilloscope to measure analog signal coming from a sensor, in this case from phototransistor. From oscilloscope we could see the room lights frequency. There was a big change in signal when we applied fluorecent light of the work station. The wave lenght got smaller and the signal was weak compared to overhead lighting. Fluctuation in the signal can be seen when finger is used to block the light sensor.
Measured output from attiny45, in rx line at FTDI connector. Now it is clearly ones and zeroes. We could see the signal rate from the oscilloscope it was 112 µs. We can see that the signal starts with 0 and then the actual data sending begins.